The subject matter disclosed herein relates generally to the use of sensors capable of measuring both flow and concentration in a medical gas mixer, such as may be part of an anesthesia machine.
Conventional gas mixing devices, such as those used in the administration of anesthesia, typically blend together two or more known gases. Each gas is generally separately sourced and provided by a respective mixer input. After blending, the gases may be output as a mixed gas at a mixed gas channel output and may be administered to a patient.
In conventional mixer technology, prior information of each input gas identity and/or properties is needed for the gas mixing device to properly control flow and/or concentration of the mixed gas output. This requirement limits architectural flexibility with regards to what input gases may be sourced and dictates that they not be variable in composition. This requirement also tends to drive product cost higher (as the associated sensors must be calibrated for each specific possible input gas) and can result in reduced up-time, such as if an outside device is relied upon to supply the needed information about the input gas and communication with the outside device fails.
Conventional mixer technology also has other limitations. For example, in conventional architectures, additional sensors may be employed at the mixing device output so as to both provide control of flow and concentration at the device output and to provide an independent, redundant measurement of concentration for patient safety. In addition, providing accurate control of flow and/or concentration at the device output typically requires precise measurement of one or more local environmental conditions for the gas at both the input and output of the device. These additional requirements also act to increase system complexity and cost.